Just a little Sherlock/John oneshot inspired by sash-kash(dot)deviantart(dot)com/art/Experiments-are-Fun-213594670 (Go look! It's hilarious)

There was a sudden eerie pause in the tapping that was coming from the seat to his left. John Watson froze and flicked his eyes up the ceiling in annoyance.

"What is it?" he asked dully. The rain was snapping against the windows of the cab in less a steady London-normal beat, more a constant whiplash of a thousand tiny bullets of water slamming into them. He pitied the cabby. Actually, worse than having to drive through this torrential downpour was having to walk in it. In the short distance between 221b and the cab at the curb John had been soaked through from the rain above, sunk his left trouser leg almost entirely into street-edge puddle below, and just avoided being drenched in the splash-up from a passing van.

Naturally Sherlock was spotless.

"Out with it Sherlock."

He didn't respond. John turned his head warily and found that Sherlock was staring at him likewise, the difference being that whereas John looked suspicious, Sherlock's smirk was downright devious and a manic gleam was already beginning to glisten in his eyes. He raised his eyebrows and slid a single pale digit over to his phone screen, tapping once. The once bright screen, that even John had to admit was casting a slightly murderous shadow on his flatmate's face, blinked once and then went darker.

"For God's sake Sherlock, stop looking at me like that and tell me what you're doing!"

Sherlock appraised his outburst and bearing silently for a moment before opening his mouth and responding with a tilt of his head, "I'm not doing anything."

"Of course you're not," John huffed and settled back into his seat. He crossed his arms over his still damp jumper and frowned down at the cab floor. "Yet."

"Mm yes, well, if you would have a little bit of patience, John," he said, fiddling with the sleeve of his coat so his thumb extending out over the screen and his wrist rested on the seat in front of him, "you would soon find out what it is that I am planning on doing at some point in the very near future, but which I have not yet done."

"Must you always be so pedantic?"

Sherlock opened his mouth to reply, but John held up a hand. "No, forget I asked." Said hand moved back to John's face to irritably scrub back a bit of bangs that was dripping rainwater into his eyes. With that done he looked back at Sherlock expectantly.

"I would like to conduct a... social experiment, of sorts," Sherlock said, thumb hovering nervously over his phone screen. "Would you care to assist?"

There were two things there should have put John off; the first, the fact that Sherlock was bothering to ask if he would do something, rather than his usual taking off and expecting John to follow along in his coat-swishing wake. Which he always did, of course, but that was beside the point. Sherlock Holmes hardly ever asked John for his help- if he did it was either sarcasm or part of proving a point.

The second was the thumb, that tense thumb on the phone that was facing the wrong way entirely, as if waiting for something. Another thing Sherlock Holmes hardly ever did was get nervous. It wasn't in his nature. He got frenzied sometimes, impatient often, but nervous never.

But because John was John and not Sherlock (who would have recognized and evaluated all of this in an instant) he did not notice either of those things.

"Yeah, alright."

"Good," Sherlock said shortly and in an instant a hand was wrapped into the front of his jumper, yanking him forward with a jolt. Lips pressed briefly (all too briefly, he tried not to think) against his, there was a flash of light, and then it was over and John was leaning forward over open air.

John sat stunned in that position for several long seconds before numbly falling back into his seat. To his side Sherlock was happily tapping away at his phone again, a smug grin in place. John used what seemed to be an inordinate sum of energy to raise his arm and allowed his fingers to trace lightly along his mouth. A movement, he realized, that would not go unnoticed by Sherlock.

"What... the hell was that?" John managed weakly, moving his hand away from his face.

Sherlock sighed heavily, and tossed his phone down. He threw a look of utter exasperation at John and replied, "I told you - it was a social experiment. You don't have to look so shocked, I did warn you." He went back to his typing.

"Wa-warn me?" John spluttered, indignant. "That was not a warning!" He jabbed a finger at Sherlock. "You asked if I wanted to help with and experiment and then you just... so you could go right ahead and snog me!"

"Ooh, well deduced John."

"So I'm right?" John said, scrunching his forehead in disbelief. "You went through all of that effort, tapping away on the phone, going on about with that rubbish about a social experiment-"

"It was."

"Sorry?"

"It was a social experiment." Sherlock's eyes never left his phone, still furiously typing away, but John spotted the very tips of his ears turning a pale pink.

John laughed humorlessly. "Oh okay, alright, and what exactly did you conclude from it?"

"Nothing."

"Nothing?"

"Yet. I never said I was done with the experiment."

John's eyebrows disappeared into his bangs. "Whoa, I did not agree to-"

"Don't sound so alarmed John," Sherlock cut across, now looking a little angry, "this has nothing to do with you."

"What-"

"I wanted to see other people's reactions," he explained, glancing at John. "And, seeing as it's something they so often assume is already going on, I thought it might be interesting," he tilted the phone towards John, who gaped at the picture displayed there. "Like I said, nothing to do with you."

"Like hell it doesn't! I'm the one who's in the bloody picture!" John leapt forward over Sherlock and ripped the phone out of his hands. Sherlock looked affronted and glared at him.

"Molly, Mrs. Hudson, Donovan... damn it Sherlock! Lestrade?"

"I needed a wide sample size," he said, looking longingly at his lost phone.